The most common and most likely answer to this crossword clue is the 2 plus 9 letter word GO OVERBOARD
I've seen this crossword clue in The Daily Telegraph
G
O
O
V
E
R
B
O
A
R
D
More clues leading to the result GO OVERBOARD
Buddy explains!
The straight part
We know that "Fall from vessel/get carried away" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fall from vessel/get carried away = go overboard.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.